The stockless anchor consists of a heavy head in
which the crown, tripping palms, and flukes are forged
in one piece. This unit is pivoted on the shank so that it
can swing from 45° to either side of the shank. The
flukes are large and long, and projecting shoulders or
tripping palms are cast at the base of the flukes to make
them bite. As the force of the drag exerts itself, the
shoulders catch on the bottom and force the anchor to
take hold by pushing the flukes downward into the
bottom. Because an upward pull on the shank of a
stockless anchor has a tendency to break out the flukes,
a long scope of chain must be used to make sure the
shank remains on the bottom when the anchor is set.
With too short a scope, or even under a steady pull with
a long scope, a stockless anchor may still disengage its
flukes as a result of gradually turning over and rolling
out. Under this condition, the anchor can offer no
resistance to dragging except by its weight.
Two types of lightweight anchors are used on Navy
ships: the Mk 2 LWT and the wedge block LWT anchor.
These are shown in views D and F of figure 4-1.
Lightweight anchors are constructed of compar-
atively light metal, but are very strong in tension. They
gain their holding power by digging deep into the
bottom rather than lying as a deadweight.
Both the Mk 2 LWT anchor and the wedge block
LWT anchor have high holding power for their weights.
The 30° fluke angle on the wedge block LWT anchor is
most effective in sand bottoms; and the 50° fluke angle,
in mud bottoms. For example, both 10,000-pound LWT
anchors are designed to have a holding power in a sand
bottom slightly higher than the 22,500-pound standard
Navy stockless anchor. They are used as bower and
stern anchors and may also be used as stream or kedge
anchors. Anchors less then 150 pounds are normally
used as small boat anchors.
The main characteristic of the LWT anchor is the
placement of large flukes at such an angle that they
drive deep into the bottom to ensure good holding
power. The crown is designed to lift the rear of the
flukes and force their points downward into the bottom.
Good stability is also obtained by placing the flukes
close to the shank.
These anchors are extremely useful in any situation
where lightweight but good holding power is essential.
They have even been cast up to 3,000 pounds for use as
stern anchors on LSTs. For Navy use, LWT anchors are
made in approximate weights from 8 pounds to 13,000
pounds, for the Mk 2 LWT 6,000 pounds and 30,000
pounds for the wedge block LWT. The commercial
Danforth anchor, shown in view E of figure 4-1, is used
on some Navy craft and small boats.
The two-fluke balanced-fluke anchor (view G of
figure 4-1) is used for anchoring some surface ships and
the newer submarines and is normally housed in the
bottom of the ship. This anchor is used on certain
combatant-type surface ships in place of a bower
anchor, which could interfere with the ship's sonar
Old-fashioned, or stock, anchors (view H of
figure 4-1) have been abandoned by large merchant and
Navy ships because they are extremely cumbersome
and difficult to stow. Because of their superior holding
power, stock anchors are still used on some boats, and
yachtsmen use them for small craft.
Mushroom anchors are shaped like a mushroom
with a long narrow stem serving as the shank. Because
of their excellent holding ability, they are used for
permanent moorings and as anchors for channel buoys
and other navigational aids. The mushroom anchor
(view I of figure 4-1) is used to anchor buoys and
torpedo testing barges. The rounded part, or crown,
strikes the bottom first, and the upper surface of the
mushroom is cupped to provide a biting surface. As the
anchor shifts back and forth under strain, it digs itself
deeper into the bottom, thereby increasing its holding
power. Consequently, it takes a firm hold and remains
fixed under the most adverse conditions. Because the
mushroom anchor has no projecting stock or flukes to
foul, the moored object can swing freely around a
mushroom anchor. However, since a mushroom anchor
will break out if the direction of pull is reversed, it is
normally used only in groups of three or more,
surrounding the central mooring point. Certain older
class submarines use this type of anchor.
CHAIN AND APPENDAGES
Present day Navy anchor chain of the flash butt
welded type is the Navy standard for new ship
constructions and replaces die-lock chain as required